1. Field of the Invention
The subject invention relates to a fuse assembly with integrated current sensing, primarily for use in the drive system of an electric or hybrid-electric vehicle.
2. Description of the Related Art
With the electrification of the drive systems of vehicles, there are several problems with the state of the art in current sensing methodologies. Given the high currents present and the need to sense the DC current, there are basically two options: (1) Non-contact Hall effect sensors or (2) Inline current shunt resistors.
Hall effect sensors have three primary problems. First, the sensors rely on sensing a static magnetic field. This static magnetic field can be affected by an external field imposed on the drive system and also by switching noise on the lines themselves. Second, depending on the design, Hall effect sensors are sensitive to the mechanical mounting of the system and can exhibit variations based on their installation methods. Third, Hall effect sensors are less accurate than equivalent current shunt methodologies.
Inline current shunt resistors have their own limitations. The dissipation power caused by the current requires that the resistance of the resistive element be of an extremely small value. This means that a metalized shunt is required to maintain a reasonable size. This thermal profile generally also requires the shunt to be mounted off-board or in a leaded device, i.e., a device with electrical conductors connected to the device.
Second, it is necessary to physically insert the resistance of the current shunt resistor into the current path. This both adds to the mechanical complexity, and adds additional impedance into the drive system. The impedance comes as both the resistance of the element, as well as in additional connection points in the system. Third, if the shunt becomes thermally stressed due to an over current conditions, its electrical resistance changes.
There is a current need for improved sensing devices that will eliminate one or more problems associated with the prior art sensing devices.